Ventilatory settings in the initial 72 h and their association with outcome in out-of-hospital cardiac arrest patients: a preplanned secondary analysis of the targeted hypothermia versus targeted normothermia after out-of-hospital cardiac arrest (TTM2) trial

Abstract

Purpose:The optimal ventilatory settings in patients after cardiac arrest and their association with outcome remain unclear. The aim of this study was to describe the ventilatory settings applied in the first 72 h of mechanical ventilation in patients after out-of-hospital cardiac arrest and their association with 6-month outcomes.Methods: Preplanned sub-analysis of the Target Temperature Management-2 trial. Clinical outcomes were mortality and functional status (assessed by the Modified Rankin Scale) 6 months after randomization.Results: A total of 1848 patients were included (mean age 64 [Standard Deviation, SD = 14] years). At 6 months, 950 (51%) patients were alive and 898 (49%) were dead. Median tidal volume (V T ) was 7 (Interquartile range, IQR = 6.2-8.5) mL per Predicted Body Weight (PBW), positive end expiratory pressure (PEEP) was 7 (IQR = 5-9) cmH 2 0, plateau pressure was 20 cmH 2 0 (IQR = 17-23), driving pressure was 12 cmH 2 0 (IQR = 10-15), mechanical power 16.2 J/min (IQR = 12.1-21.8), ventilatory ratio was 1.27 (IQR = 1.04-1.6), and respiratory rate was 17 breaths/minute (IQR = 14-20). Median partial pressure of oxygen was 87 mmHg (IQR = 75-105), and partial pressure of carbon dioxide was

Oxygen targets and 6-month outcome after out of hospital cardiac arrest: a pre-planned sub-analysis of the targeted hypothermia versus targeted normothermia after Out-of-Hospital Cardiac Arrest (TTM2) trial

“…When building a regression model, the process of variable selection comprised an initial model with: (1) patients' clinical characteristics (age, sex, body mass index-BMI, height, Charlson comorbidity index, state of shock at admission, and STEMI diagnosis on admission); (2) onsiterelated cardiopulmonary resuscitation (CPR) related variables (ROSC time, bystander CPR, OHCA physical location, initial cardiac rhythm, witnessed OHCA); (3) treatment variables from the original trial (randomization arm and tympanic temperature at admission); and (4) ABG values and ( 5) ventilatory settings parameters. From this initial set of covariates, a more parsimonious model was developed by backward elimination using a multivariable fractional polynomial (FP) procedure [27]. The linearity assumption of continuous variables was tested, and the variable transformed with the appropriate FP when the assumption was not met.…”

“…Several studies highlighted the importance of maintaining appropriate ventilation targets and levels of PaO 2 in OHCA patients [27]. Post-cardiac arrest syndrome includes a number of pathophysiological mechanisms such as brain edema, reperfusion injury and oxidative stress, which can lead to neuronal damage and brain injury [28].…”

Updates on Post-Resuscitation Care. After the Return of Spontaneous Circulation beyond the 2021 Guidelines

“…In a secondary analysis of three prospective, observational multicenter studies including 812 patients from 1998 to 2010, demonstrated that a significant reduction in tidal volume, peak and plateau pressure, and a significant increase of respiratory rate and PEEP were observed over the years [57]. A recent secondary analysis of the TTM2 trial showed that respiratory rate, driving pressure (plateau pressure -PEEP), mechanical power and ventilatory ratio are independently associated with 6-month mortality with the formula [(4 × Driving Pressure) + RR] being also associated with mortality and poor neurological outcome [58]. However, mechanical power and ventilatory ratio are not universally applied as part of the daily routine at bedside.…”

The importance of ventilator settings and respiratory mechanics in patients resuscitated from cardiac arrest

“…In this issue of the journal, Robba and coworkers [16] report the results a pre-planned secondary analysis of a large trial investigating targeted temperature management in critically ill patients resuscitated from OHCA, which aimed to assess the association between ventilatory variables and clinical outcome (6-month mortality and neurological status). They studied 1848 patients and showed that respiratory rate, ΔP and mechanical power were independently associated with 6-month mortality; respiratory rate and ΔP were also independently associated with poor neurological outcome, and their combination in the formula (4*ΔP + respiratory rate) had the strongest association with both 6-month mortality and poor neurological outcome.…”